1. Field of the Invention
This invention relates to new and useful epoxy resin compositions, especially those capable of being cured to solid resins which are highly resistant to boiling acetone and are lighter in color. Epoxy resins are well-known in the art and comprise a molecule which contains on the average more than one epoxy group. The resins are converted into hard, infusible cross-linked polymers by curing. Curing of the resins can be effected, for example, by a catalytic polymerization process or by a coupling process. The compositions of the present invention are formed by the coupling process wherein the epoxy resin is reacted with specific poly-functional cross-linking agents to couple or cross-link one epoxy resin molecule with another.
The properties of the epoxy resins and the finished polymers will depend, of course, on the nature of the epoxy resin and the cross-linking agents. For some applications, for example, encapsulation and bonding, it is desirable that molded products and powder coatings be highly resistant to chemicals and solvents, especially boiling acetone (U.S. Pat. No. 3,324,081) and that epoxy compositions be light in color. To supply this need, the present invention herein provides a new composition capable of being cured to a solid highly resistant to boiling acetone which comprises (a) a 1,2-epoxy resin containing on the average more than one 1,2-epoxy group per molecule; (b) a residue remaining from the process wherein cumene (C) is reacted with maleic anhydride (MA) in the presence of (that is, in contact with) zinc chloride to obtain a reaction product containing dimethylbenzyl succinic anhydride (DMBSA), 5-phenyl-5-methylhexane-1,2,3,4-tetracarboxylic acid dianhydride (PMTD) and addition products of C and MA containing more than two anhydride groups per molecule (AP) and wherein a sufficient amount of said DMBSA is removed from said reaction product to give a residue containing a maximum of 25 weight percent DMBSA; and (c) an accelerator.
2. Description of the Prior Art
Applicant is unaware of any prior art relevant to the invention defined and claimed herein.